Answers to general HVAC, water heater and plumbing questions
- Should I repair or replace my furnace or air conditioner?
The age of your furnace or air conditioner matters in your decision
If your furnace or air conditioner is 10 years old or older, it may be time to start thinking about upgrading. There have been several technological advances over the past decade that have increased both the energy and operational efficiency of the units. Today's models can help you save on operating expenses, are better for the environment and deliver better overall comfort.
Some recent furnace and air conditioner advancements
Here are just a few of the things that have changed over the years:
- All residential gas furnaces must be condensing as of 2009.
- As of December 19, 2019 the minimum AFUE ratings for residential gas furnaces was raised to 95%
- The requirement of DC variable speed or ECM blower motors in all furnaces as of July 3, 2019
- Minimum SEER ratings for air conditioners of at least 13
- The introduction of variable speed compressors in central air conditioner systems
- How much could I save on my gas bill by upgrading to a high efficiency furnace?
Calculating the savings for furnace upgrades
It’s simple to calculate just how much you could be saving by upgrading your existing furnace to an Energy Star® rated high-efficiency model:
Annual $ savings = (A-B)/A x C
A = Efficiency of the new system
B = Efficiency of the existing system
C = Your current annual heating cost to run your furnace
Example: How much could you save by switching from a 60% efficient conventional gas furnace to an Energy Star® rated high-efficiency gas furnace at 92% efficiency if your annual gas bill for heating is $1,000?
Therefore, A = 92%, B = 60% and C = $1,000
Annual $ savings = (92-60)/92 x 1,000 = $348
This means you could save up to $348 a year in gas costs by upgrading to an Energy Star® high-efficiency gas furnace.
- How much could I save on my hydro bill by upgrading my air conditioner?
Calculating the savings for air conditioner upgrades
It’s simple to calculate just how much you could be saving by upgrading your existing air conditioner to a more energy efficient model:
Annual $ savings = A – B
A = spend per year with your old system
B = spend per year with the new system
A and B are calculated in the same way and as follows:
A or B = (BTU size of the air conditioner)/(SEER rating) ÷ 1,000 x (electricity price per kWh) x (number of hours the air conditioner is used per year)
Note: 1 ton = 12,000 BTU
Example: How much could you save by switching from a 2 ton 10 SEER air conditioner to a 2 ton energy efficient air conditioner at 13 SEER if your electricity cost is $0.10/kWh and the air conditioner gets used 2,160 hours per year (on 24hrs/day for 3 months)?
A = 24,000BTU/10 SEER ÷ 1000 x $0.10/kWh x 2160 hrs = $518.40
B = 24,000BTU/13 SEER ÷ 1000 x $0.10/kWh x 2160 hrs = $398.77
Annual $ savings = $518.40 - $398.77 = $119.63
This means you could save up to $119.63 a year in electricity costs by installing a more energy efficient air conditioner.
- What is an AFUE (Annual Fuel Utilization Efficiency) rating for a furnace?
AFUE and furnace efficiency
The Annual Fuel Utilization Efficiency or AFUE (pronounced ‘A’-‘Foo’) rating for a furnace is the most widely used measure of a furnace’s efficiency. It denotes the actual amount of heat that gets delivered to your home versus the amount of heating fuel that you must supply the furnace.
If you were to look at this in dollars and cents, an example would be for a 95% efficient gas furnace, $0.95 of every dollar you spend on heating gas actually goes into heating your home. Compare this to a 60% efficient furnace where $0.40 of every dollar you spend on fuel is heading straight out of your chimney.
The minimum efficiency standard in Canada for natural gas units being installed in new homes is currently 95%. Most furnaces manufactured before 1990 where 60% efficient. Furnaces manufactured today have AFUE ratings that range from 95% to as high as 98%.
- What is a SEER (Seasonal Energy Efficiency Ratio) rating for an air conditioner?
SEER and air conditioner efficiency
Cooling efficiency for air conditioners is indicated by a SEER (Seasonal Energy Efficiency Ratio) rating, which tells you how efficiently the unit uses electricity. The rule for saving is simple—the higher the SEER rating, the less energy you use and the more you save.
The minimum efficiency standard for units installed in new homes is currently 13 SEER. Most air conditioners manufactured before 1992 had SEER ratings below 7. Air conditioners manufactured today have SEER ratings that range from 13 to as high as 26 in some units.
- What is a DC (Direct Current) variable speed or ECM (Electronically Commutated Motor) blower?
DC (Direct Current) variable speed or ECM (Electronically Commutated Motor) central heating or cooling system blowers
In essence, the DC variable speed or ECM blower in your central heating and/or cooling system is a much more energy efficient way of pushing the air through your home. In single or multi-speed blowers you are left with set speeds at which the blower must run. That means that your system has to pick one of the set speeds to operate on independent of whether or not that much power is actually needed to get the temperature of your home back to your thermostat settings.
In contrast, with DC Variable speed or ECM blowers, any multitude of blower power settings are available which means that your heating and/or cooling system can use less power more often to keep your home’s temperature constant. An added benefit to these types of blowers is that they ramp up to speed which means they are much quieter than their set speed counterparts.
- What is a condensing furnace?
Higher efficiencies through the process of condensing in furnaces
A condensing furnace is the technology that allows modern furnaces to achieve efficiencies above 90%. It works by forcing the hot exhaust gas created by the furnace’s burners through a specialized heat exchanger designed to increase the pressure on that hot gas to the point that it forces a change of state of the gaseous water present in the exhaust into a liquid. When this change of state occurs, a large amount of energy is released in the form of heat. So not only do you get the heat from the burning source fuel, you also get the heat from this chemical change of state. The resulting liquid water that is created is drained out of the furnace. The heat created is transferred over to the cooler air of your home and what you are left with is a combustion waste gas that gets expelled from the system. Because of how efficient this condensing action is, the resulting combustion waste gas is so cool that it can be passed through plastic piping to the outside; this means you don’t need a traditional chimney.
- What is EER (Energy Efficiency Ratio)?
EER (Energy Efficiency Ratio) another measure of your air conditioner’s energy efficiency
Sometimes cooling devices such as central air conditioning systems are rated using EER (Energy Efficiency Ratio) versus SEER (Seasonal Energy Efficiency Ratio). EER is a measure of how efficiently an air conditioner will operate when the temperature outside is at a specific level – the higher the EER, the higher the efficiency of the unit. The main difference between the two measurements is that EER measures efficiency at peak day operations while SEER measures efficiency over the entire cooling season.
- What is a BTU (British Thermal Unit)?
The BTU measure of power for furnaces and air conditioners
The British Thermal Unit, or BTU for short, is a traditional measure of energy. In North America, it is commonly used to describe the power of heating and cooling systems. When used to describe power, BTU per hour (BTU/hr) is actual the technically correct unit, but it usually gets abbreviated to simply BTU.
The BTU also tends to be more commonly used with furnaces rather than air conditioners, which tend to get described in tons instead. Nevertheless, it is an easy conversion since 1 ton is equal to approximately 12,000 BTU. The higher the BTU rating of your system, the larger its heating or cooling capacity (meaning it can handle bigger areas) and the more energy it uses. This is why proper furnace and air conditioner sizing is so important.
- What is a ton?
The ton measure of cooling capacity for air conditioners
In North America, air conditioner equipment power is often described in tons of refrigerant. A ton of refrigerant is defined as the cooling power of one ton of ice melting in a 24 hour period. 1 ton is also equal to approximately 12,000 BTU. In the HVAC industry we throw around the term ton to describe the size of the air conditioner you need. In other words, the greater the number of tons of the unit, the larger the capacity of the unit which means the bigger the area it can cool. The larger the ton rating, however, the more energy the unit will use. This is why proper furnace and air conditioner sizing is so important.
- What is a refrigerant?
The stuff that enables my air conditioner to cool my house
A refrigerant is a compound that is used in air conditioning systems to absorb and release heat. It does this by changing states from a gas to a liquid using a compressor. In a central cooling system, the compressor, which is usually located outside, compresses the refrigerant gas into a liquid and pumps it into a coil usually located inside your home on top of your furnace or air handler. The warm air from your house then passes over this coil containing the compressed liquid gas which absorbs the heat from this warmer air and changes state back to a gas (in essence a boiling process). This gas is then pumped back outside to the compressor which turns it back into a liquid thus releasing all of the heat energy it had absorbed to the outside environment.
- What does HVAC stand for?
Heating, Ventilating and Air Conditioning – HVAC
HVAC is an acronym that stands for Heating, Ventilating and Air Conditioning. The heating and cooling industry often labels itself with this acronym. In fact, furnace and air conditioner sales, installation and repair companies will also classify themselves as HVAC contractors.
- How do I size my new furnace or air conditioner?
The proper sizing of your furnace or air conditioner will determine how much usable efficiency you get out of them
Having a furnace or air conditioner of correct size will result in much more efficient operation during the seasons in which they are used. Oversized units will only run for short periods of time which means they will never run in their peak efficiency modes. Rather, they will always be used in the less efficient start up phase of operation. Conversely, undersized units will stay running much too long, and as a result not only be inefficient, but may also be more prone to breakage due to over exertion.
So, how do you size your equipment? The best and easiest way to do this is by having a contractor use a home heat loss calculation that is available from the Canadian Standards Association (CAN/CSA F280) or a sizing procedure from the Heating, Refrigeration and Air Conditioning Institute of Canada (HRAI).
- How does my central air conditioner work?
Compressor, evaporator or A-coil, blower, they are all part of your central air conditioning system
A central air conditioning system actually works by removing the heat from the air in your house, not by manufacturing additional cold air and introducing it to your home. In order to make this removing of heat take place, you require three main components: 1) a compressor which usually sits on a concrete slab outside of your home, 2) an evaporator coil (sometimes called an A-coil because it is in the shape of the letter A) which sits atop your furnace inside your home and 3) a blower to both pull in the warm air and re-circulate the now cooler air through your home. This blower is usually found inside of your furnace, so parts of your furnace in effect help to cool your home.
Here is how all of these components work together to cool your home. First, the compressor outside compresses the refrigerant gas in the system and turns it into a liquid. This liquid gets pumped into the evaporator coil inside your home. The blower (for all intents and purposes, your furnace) then pulls the warm air from your home into the system and pushes it over the coil. As this warm air passes over the coil the heat from it gets absorbed by the refrigerant liquid causing it to boil and change state back into a gas. This gas then gets pumped back outside to the compressor where it is compressed once again into a liquid. This second change of state, from gas to liquid, releases to the outside environment all of the heat that the liquid absorbed from inside of your home.
- How does my high-efficiency furnace work?
Demystifying how today’s high-efficiency furnaces make it all happen
Your gas furnace is made up of the following major components: a heat exchanger, a blower (or fan) and a burner. So let’s start with the air flow, your blower accomplishes two jobs at once, 1) it pulls in the air from your home into the furnace itself and 2) it blows that air up through the furnace to get heated and then back into your home.
The heating part of the process starts with the ignition of the gas that is released through the burner which is usually situated at the top of the furnace’s heat exchanger. Today’s modern furnaces do not have pilot lights but rather electronically ignite the gas as it is released by the burner valves. Furthermore, they pull in either fresh air from outside or ambient air from around the furnace itself to aid with more complete combustion.
Now that the burner is lit, a small fan situated at the bottom of the heat exchanger pulls this heated gas down through it. This is a good place to give a quick explanation of what exactly a heat exchanger is.
In essence, the heat exchanger is a chamber around which the cooler air from your home mixes with and absorbs the heat created from the hot gas produced at the burner. In high efficiency systems the key is to keep this hot gas in the exchanger as long as possible so that the maximum amount of heat can be transferred over to the cooler air. This is achieved by creating bends and curves in tubing through which the heated gas passes through to both create a longer distance to travel and to slow the rate at which it passes over this distance. This is also why the burner is usually located at the top of the heat exchanger and has a small fan at the bottom of it pulling it down through the exchanger. This way we can fight gravity and pull the gas downward which helps keep it in the chamber longer. The cooler air from your home is then passed over these now hot tubes allowing for the heat transfer.
The highest efficiency furnaces (condensing furnaces) actually have a secondary heat exchanger that further compresses the hot gas to the point of condensing the water vapour contained in it into liquid water. This chemical change of state releases heat energy in the process over-and-above the heat generated from the burners alone.
- How do I find out how efficient my furnace or air conditioner is?
Finding out the efficiency of your furnace or air conditioner
The simplest way to find out the efficiency of your heating and cooling equipment is to go to the equipment itself and see if it is listed there. If not, then look for a model or serial number on the furnace and/or one on your compressor outside. Go to the manufacturer’s website for your particular piece of equipment and search that model or serial number. If nothing comes up, contact the manufacturer with this data and ask for the efficiency ratings.
In terms of determining if you have a high-efficiency furnace, a quick visual indication of this will be plastic venting pipes that extend from your furnace to the side of your house and outside versus going up through a chimney that exits at your roof.
- What is a MERV rating?
Minimum Efficiency Reporting Value (MERV)
The Minimum Efficiency Reporting Value or MERV rating for short is a measurement of the ability of an air filter to capture particles. The higher the rating, the smaller the particle the filter can capture and hence the more particulate pollutants the filter can remove from the air.
- What is a HEPA filter?
High Efficiency Particulate Air filter (HEPA)
High Efficiency Particulate Air or HEPA filters for short are air filters that are able to trap 99.97% of particles that are as tiny as 0.3 microns in size. This is the size of particle that has been determined to be the hardest size to trap and the optimal size for passing into the human respiratory system.
- What are VOCs?
Volatile Organic Compounds (VOC)
Volatile Organic Compounds or VOCs for short are emitted as gases from certain solids or liquids, many of which you may find in your home. Some of these VOCs can have adverse short and even long-term health effects. Paints, new carpets, adhesives, pesticides and even cleaning supplies can all emit harmful VOCs into your home’s atmosphere.
- How does my water heater work?
How we make hot water
Water heaters can be classified into two broad categories: 1) the storage type which are built around a storage tank of some sort which is filled with water that gets heated waiting to be used, this is the most common type of water heater; and 2) on-demand or tankless water heaters that don’t have storage tanks and heat the water as it flows through them for use.
Let's start with the common storage type. This type of water heater is usually powered by either electricity or gas with the gas type having a burner at the bottom of the tank and the electrical ones having elements submerged in the tank. Both types operate on the same basic principle, cold water is piped into the tank where it is heated by either the burner (gas water heater) or the elements (electric water heater), starting a convection process that mixes the tank contents until the target temperature is reached. The heated water then waits to be used. As it sits waiting, there is a certain amount of stand-by heat loss that occurs which will eventually lower the temperature below the target setting. When this happens, the water heater turns back on to heat the water back up to the target temperature. This cycle occurs continuously which means that the tank is continuously using energy throughout the day.
In tankless models, the tank turns on once it receives a call for hot water (that's you turning on a hot water tap in your house, the flow of water turns the tank on). The tank then quickly heats up water from the water main as it passes through it. This means that it uses quite a bit of energy as it is running, but you save on all of the time that you are not using hot water since the tank is off. Another big benefit is that you have an endless amount of hot water at your disposal since you are not limited to an amount that is sitting in a storage tank.
- How does my tankless or on-demand water heater work?
Here’s how a tankless water heater system gets it done
In a tankless system, the water gets heated as it flows through the system. This does not mean that the water is instantly hot when it comes out of the tap. It still takes time for the newly heated water to make it through the piping in your home to the place where it is going to get used.
So here is how they work:
- When you turn on your hot water tap the flow of water signals the tankless water heater to turn on.
- Now, depending on the temperature of the incoming cold water and the temperature you’ve set on your unit’s thermostat, the gas flow into the burner assembly gets controlled.
- Next, an electronic igniter lights the incoming gas through the burner.
- The burner heats up a heat exchanger that has the cold water flowing through it to get it to the proper temperature, providing you with as much hot water as you need.
- When you turn off your tap, the stop in the flow of water signals the tankless water heater to turn off.
- What are all of the components of my storage tank water heater?
The components that make up your gas storage tank water heater
- The tank jacket (the outside of the tank) is made of steel and encloses a pressure tested water storage tank (usually glass or plastic lined).
- Between the storage tank and the tank jacket is insulation to reduce heat loss of the heated water. You can supplement this insulation by adding a fibreglass insulation tank jacket to the outside of the hot water heater, but only if the Use & Care Manual for your water heater states that this is allowed. Generally this is allowed with electric water heaters but not with gas water heaters.
- Inside the tank is what is called a dip tube. The dip tube is where the cold water supply enters the tank to be heated by the gas burner. The cold water is denser than the hot water so the cold water drops to the bottom of the tank until it is warmed by the burner and heated enough to rise to the top of the tank where the hot water gets extracted for use.
- In glass-lined tanks there is a metal rod inside (usually magnesium or aluminum) called a sacrificial anode. The anode rod is fastened to the top of the tank and extends down into it. The purpose is to draw minerals and corrosion to it instead of the metal tank. Some models do not have a separate anode but combine the function of the anode with the hot outlet. Plastic lined tanks do not have an anode
- The natural gas or propane is supplied by a pipe having its own gas shutoff valve. Just like you need to know where the water supply shutoff valve is located, you need to know where the gas line shutoff is located as well.
- The gas line feeds into a gas burner control module that serves as a thermostat for the water heater. It also controls the ignition of the pilot light.
- From the control module we now proceed to the gas burner assembly. This includes the pilot light or electronic igniter and the gas burner.
- The exhaust flue serves two purposes. It exhausts combustion gasses from the burner and it serves as a type of heat exchanger helping to heat the water in the storage tank. The flue must be properly exhausted to the outside.
- A pressure relief valve located at or near the top of the tank used as a failsafe should pressures in the tank rise above normal.
- The tank drain valve is located at the bottom of the tank and is used to drain the tank of its contents.
- At what temperature is my water heater set?
Water heater temperature settings
All water heaters come with a factory preset temperature setting of 60° C (140° F). This is the manufacturer's recommended setting and provides the right temperature for washing, bathing and for bacteria control.
However, hot water can produce severe burns. If scalding is a concern with children or the elderly, a qualified professional can adjust the temperature to no lower than 50° C (122° F).
You can also install anti-scalding devices on shower heads, faucets and bathtub spouts to shut off the water flow if the temperature exceeds 49° C (120° F). A master mixing valve can also be installed at the hot water line running from the water heater. These devices provide a safe compromise that allows your water heater to be operated at 60° C (140° F) for bacteria control, while delivering actual water to be used at less than 50° C (122° F).
- What’s the additional cost of operating a 60 gallon versus a 40 gallon water heater?
Operating costs of different sized water heaters
There is minimal cost difference between different sized water heaters. The only difference in energy costs relates to the difference in stand-by heat losses.
Stand-by losses are caused when the water heater inside temperature is higher than the outside temperature. A 60 gallon water heater has an average loss of 116 watts, while a 40 gallon size has an average loss of 96 watts, as an example. Comparatively, the approximate savings in stand-by losses to go from a 60 to 40 gallon size is $6.85 versus $5.67 – a difference of $1.18 per month.
- I recently purchased a new high efficiency furnace and my contractor tells me I should switch to a power vented water heater. Is this necessary?
Upgrading your furnace may mean upgrading your water heater as well
If you upgrade a conventional furnace (chimney exhausted) to a high efficiency furnace that doesn't use the chimney for venting, you often times need to upgrade your water heater as well if it too exhausts through the chimney. This is a gas code requirement, since removing the furnace exhaust will create the potential for negative pressure in the chimney allowing for carbon monoxide to enter the home. To avoid this, upgrading to a power vent water heater model is a good alternative, since it will not require the chimney for venting. If upgrading your conventional water heater is not something you're interested in, then you will need to have a chimney liner inserted that narrows the chimney diameter as a means to eliminate a negative pressure environment.
- I’ve been told that power vented water heaters are high efficiency water heaters just like my furnace. Is this true?
Your water heater’s vent doesn’t tell you how efficient it is
A power vented water heater is not more efficient. It may use less gas because it does not have a pilot light, however, you will now be using electricity to power the blower motor, which is an additional expense. The retail value and service costs are slightly higher on a power vented water heater, as compared to a conventional water heater, but the efficiency is not that much higher, if at all.
- I’ve heard that tankless water heaters are more efficient and will provide my family with the hot water we need. Is this true?
Tankless water heater efficiency depends on your usage
The efficiency you get from a tankless water heater really depends on how you consume hot water in your home. The big energy savings you get from the unit really come from when you are not using it. In fact, they probably use more energy than storage tank models when heating the water since they require so much power to heat the water quickly. The advantage comes from when you don’t need hot water since the unit turns off during these periods. Conversely, in storage tank models, heating of the water is a continuous cycle, whether you're using it or not.
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